What's the difference between self-consumption and selling the surplus?

Self-consumption means using the electricity you produce on site: it saves you buying from the grid (≈ €0.20/kWh). The surplus is the share exported for lack of immediate use: it's bought back from you for less (≈ €0.10/kWh in Luxembourg, indicative). So consuming is worth about twice as much as selling.

What self-consumption rate can I expect?

Without a battery or control, expect about 30 to 40 % (the simulator uses 40 % by default). With a battery or good control of usage, 60 to 80 % is commonly reached.

Do I need a battery to self-consume?

No. You already self-consume without a battery by using production through the day. The battery raises that rate by storing the surplus for the evening. It's useful mainly if your consumption is high in the evening — its returns should be checked case by case.

How can I easily raise my self-consumption?

The simplest, free move: shift big appliances (washing machine, dishwasher, water heater, car charging) into the day. Then a solar router or a little home automation handles it automatically. The battery comes last, once the rest is optimized.

Guide GuidesSolar self-consumption: producing and using your own power

Guide · Self-consumption

Solar self-consumption: producing and using your own power

Self-consumption means using the electricity your panels produce directly at home, instead of buying it from the grid. Every kilowatt-hour consumed on site is one you don't buy — which is where most of a solar system's savings come from.

But part of the production happens when you're not consuming (midday, empty house). This surplus is exported to the grid at a lower rate. Understanding this balance — and knowing how to improve it — is the key to returns.

What is self-consumption?

Your panels produce electricity during the day. Two things can happen to each kilowatt-hour: either you consume it immediately (an appliance is running at the same time) — that's self-consumption; or no one uses it, and it goes to the grid — that's the exported surplus, which is bought back from you.

The benefit is financial. The self-consumed kilowatt-hour saves you buying from the grid, at about €0.20/kWh. The exported kilowatt-hour earns you only about €0.10/kWh. In other words, using your own production is worth roughly twice as much as selling it. Maximizing self-consumption means maximizing savings.

Self-consumption vs. selling the surplus

1 kWh self-consumed: ≈ €0.20/kWh saved (the price you don't pay the grid).
1 kWh exported (surplus): ≈ €0.10/kWh earned (surplus buy-back, indicative Luxembourg rate).
Consequence: A kWh consumed on site is worth about twice as much as a kWh sold.
Goal: Align production and consumption to self-consume as much as possible.

What self-consumption rate?

The self-consumption rate is the share of your production you use directly, without going through the grid. On a typical home, with no battery or particular control, it usually sits around 30 to 40 %: much of the midday production is simply not used on site.

With a storage battery or good control of usage (shifting big loads into the day), this rate commonly climbs to 60-80 %. The site's simulator uses 40 % by default, a realistic value for a system without a battery. Don't confuse it with the self-sufficiency rate (the share of your consumption covered by solar), which is a different measure.

Raising your self-consumption rate

Shift your usage

Schedule big loads (washing machine, dishwasher, water heater, car charging) in the middle of the day, when the panels are producing.

Free, immediate

Real gains with no hardware

Little real loss of comfort

Takes a bit of organization

Limited to movable appliances

Best for
Everyone — the first habit to adopt.

Add a battery

Store the day's surplus to use it in the evening, instead of exporting it cheaply and then buying back from the grid.

Boosts the rate (60-80 %)

Covers evening and night

Greater autonomy

Extra investment

Returns to check case by case

Best for
High evening consumption, wanting autonomy.

Control (smart home / solar router)

A solar router diverts the surplus to the water heater; home automation triggers appliances when production exceeds consumption.

Automatic, hands-off

Uses surplus without a battery

Often low-cost

A small setup is needed

Assumes controllable appliances

Best for
Optimizing without investing in a battery.

Size it right

Match the installed capacity to your real consumption. An oversized roof produces a massive surplus, sold cheap and barely profitable.

Better self-consumption rate

Better-calibrated investment

Optimized returns

Undersizing forgoes savings

A trade-off to make with a pro

Best for
Any new installation, right from the quote.

Frequently asked questions

What's the difference between self-consumption and selling the surplus?: Self-consumption means using the electricity you produce on site: it saves you buying from the grid (≈ €0.20/kWh). The surplus is the share exported for lack of immediate use: it's bought back from you for less (≈ €0.10/kWh in Luxembourg, indicative). So consuming is worth about twice as much as selling.
What self-consumption rate can I expect?: Without a battery or control, expect about 30 to 40 % (the simulator uses 40 % by default). With a battery or good control of usage, 60 to 80 % is commonly reached.
Do I need a battery to self-consume?: No. You already self-consume without a battery by using production through the day. The battery raises that rate by storing the surplus for the evening. It's useful mainly if your consumption is high in the evening — its returns should be checked case by case.
How can I easily raise my self-consumption?: The simplest, free move: shift big appliances (washing machine, dishwasher, water heater, car charging) into the day. Then a solar router or a little home automation handles it automatically. The battery comes last, once the rest is optimized.

How much could you self-consume?

Estimate your roof's production, your self-consumption rate and your savings for free — then get a quote from an installer to size it just right.

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General information for educational purposes. Rates and tariffs are indicative for Luxembourg (avoided price ≈ €0.20/kWh, surplus buy-back ≈ €0.10/kWh), to confirm against your contract and a professional quote.